P0B81Hybrid/EV Battery Voltage Sense O Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0B81 stands for an open sense lead on channel O, the fifteenth cell tap. GM has used it from the start: the 2011 Volt battery tables already list P0B81 among the open sense line codes and detect, among other cases, a busbar connection voltage above 0.7 V. In the 2019 battery energy control module the test needs 0.8 s within a 1.6 s window, with adjacent cells 1.3 V or more apart or a balancing gate below 36 mV, Type A. The BAS Plus mild hybrid compares lines N and N-1, both under 1.4 V with a change above 0.5 V in 200 ms, 7 of 10 samples, Type B. Unlike channels M and N, P0B81 does not appear in Ford's Fusion plug-in bulletin. With the lead open, the controller loses sight of that cell and limits operation.
- What you may notice
- MIL and propulsion system warning
- Reduced power or no electric drive
- Likely causes
- LikelyLoose or high-resistance busbar joint at the O tap
- PossibleBroken sense wire O in the battery harness
- RareFaulty cell sense module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €6,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.